C::B supports "multiple projects" in two ways:
1. Use of C::B project with multiple targets and one or more virtual targets combining them (take a look at the Codeblocks.cbp file to see how it is done) // I've never done such project, so I don't know the exact details
2. Use of multiple C::B projects inside a C::B workspace. // I use this approach
p.s. -Wall was missing because it is a supported option for gdc